Engine swap/check engine light?

[spacoli]

I'm recently replace the engine in a 93 p-u with a used engine (100,000mile).
My check engine light is on, so I did some research and did the jumper wire in the diagnostic box and got a two digit number, 21. Which has to do with the O2 sensor.

I'm not sure if the light was on previous to replacing the engine, since I did not own or run it.


I have been checking my gas milage and I'm getting 17mpg (city/highway), which doesn't seem to be off the norm from what I read. I would like to get more MPG if possible. I have a highway trip coming up and plan on checking highway mpg.

Should I have a shop do a diagnostic check to make sure I need a O2 sensor before I go replace it. If I do replace it, will the check engine light go off if that was the problem or will the shop need to clear it off?

Thanks

[wrnchplr]

If the motor was just replaced I would check the wire to the O2 sensor just to make sure it is plugged in.

[bodo]

Just pull the negative/black battery cable for a few minutes and see if it comes back on. The code 21 is easy to fix because 99.9% of the time it's your O2, the other .1% it's your ECU.

[spacoli]

Just got back from a 240 + mile road trip. Average speed of 45 mph GPS reading (traffic jam at rush hour hurt that avg.) Pretty much highway running with one mountain to go over both ways. My mpg come in at a few decimals over 24 mpg.

I was pretty surprised to get that high on mpg. I was expecting 20mpg, maybe 21mpg.

I still think it can run better, it seems to have a hesitation or bog at lower rpm in 2nd and 3rd gear while accelerating. I can best describe it, like a two stroke motorcycle when hitting the "powerband". Until you hit the powerband it seems boggy, but once your in the powerband your good.

I still have a low idle also.

Does this make since at all?

I really don't know how or what to expect this truck to run like, since I have not driven one before.

What do you guys think?

[wrnchplr]

Is there black smoke from the tail pipe? It sounds like the timing is off or the ing. system is worn out. mine did that tell I found the timing chain was off a tooth. the spark will advance untell you are in the "powerband" then run T&A..
that is something to check.

[spacoli]

Thanks for your reply.

No black smoke at all. I had a new timing set installed chain,gear,guides,tensioner and cover before I installed the engine.
Timing was set 5* with the jumper wire installed (short circut) in the diagnostic box, as stated on the tune up sticker under the hood.


Is there black smoke from the tail pipe? It sounds like the timing is off or the ing. system is worn out. mine did that tell I found the timing chain was off a tooth. the spark will advance untell you are in the "powerband" then run T&A..
that is something to check.